Microhard Systems MHX-910A, Руководство по эксплуатации

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12 MHX 920 Operating Manual: Chapter 3 Installation
To comply with FCC regulations,
.you must limit ERP to 36 dBm or
less.
Antenna
Before choosing an antenna, you should have some knowledge of the path
loss and the topology of the equipment. If the equipment is in a fixed
location and is to communicate with only one other unit also in a fixed
location, then a Yagi antenna is suitable. Choose a Yagi with enough gain to
ensure adequate gain margin. When deploying the Yagi, point the antenna
towards the intended target, ensuring the antenna elements are perpendicular
to the ground for vertical polarization.
In applications where there are multiple units that you must communicate
with or units, which are in motion, you may select an Omni-directional
antenna with appropriate gain.
FCC Regulations allow up to 36dBm effective radiated power (ERP).
Therefore, the sum of the transmitted power (in dBm), the cabling loss
and the antenna gain cannot exceed 36dBm with respect to the isotropic
radiator.
ERP is calculated as follows:
ERP = Tx Power (dBm) - Cable/Connector Loss (dB) + Antenna Gain (dBi)
Antenna Gains must be in dBi when calculating the 36dBm ERP limit.
1dBd = 2.15dBi
Use the guidelines in the previous section for calculating cable and connector
losses. If cabling and connector losses are 2 dB, then the maximum
allowable gain of the antenna will be 8 dB.